Conversion of hydrocarbon oils



Sept 20, 1938. K. swARTwooD I CONVERSION 0F HYDROCARBON OILS Filed Dec.24, 1934 NN ZDJOU INVENTOR KENNETH S D O m Y E W. T m

Patented Sept. 20, 1938 UNITED STATES CONVERSION OF HYDROCARBON OILSKenneth Swartwood, Chicago, Ill., assignor to Universal Oil ProductsCompany, Chicago, Ill., a corporation of Delaware Application December24, 1934, Serial No. 758,996

14 Claims.

This invention particularly refers to an improved process for thepyrolytic conversion of hydrocarbon oils accompanied by reduction of theresidual liquid conversion products of the process to substantially drycoke at relatively high temperature wherein the vaporous productsresulting from said conversion and the vaporous products resulting fromthe coking operation are commingled and subjected to continuedconversion without additional heating for the purpose of materiallyimproving the yield and quality of the nal motor fuel product of theprocess.

A recent development in the coking of relatively heavy oils, such as,for example, residual liquids resulting from the conversion of lowerboiling oils, which promises to merit wide adoption in the petroleumindustry comprises subjecting the oil in a heating coil to a conversiontemperature of the order of 950 to 1000 F., or at least sufficientlyhigh to effect its subsequent reduction to coke, without allowing itsuiiicient time in the heating coil to permit the excessive formationand deposition of coke therein. Actual reduction of the highly heatedresidual oil to coke is usually accomplished in an enlarged cokingchamber following the heating coil which may be operated at any desiredpressure ranging from substantially atmospheric to a superatmosphericpressure of the order of several hundred pounds 30 per square inch.Operations of this character normally produce a coke of more uniformquality and lower volatility than is obtained by coking methodspreviously in vogue, due to the relatively high temperature to which theoil to be 35 coked is heated as well as to the fact that the entire massof material to be coked receives substantially uniform heat treatment.It is alsobelieved that the use of relatively high superatmosphericpressures in the coking zone, which favor reduction of the residualliquids to coke by cracking, help to produce a coke of better and moreuniform quality. Heretofore, one of the chief disadvantages in thismethod of coking has been the high temperature of the vaporous productsevolved during the coking operation which necessitates largefractionating and/ or other cooling equipment.

The present invention employs the method of coking above outlined forthe reduction of the residual liquid products of the cracking operationto coke and in addition utilizes to advantage the excess heat containedin the vaporous products from the coking operation by commingling thesame with the vaporous products resulting from the cracking operationand previously separated from said residual liquids subjected to coking,the commingled vaporous products being sub-- jected to continuedconversion in a reaction chamber maintained at substantialsuperatmospheric pressure without additional heating. y

In one specific embodiment, the invention comprises subjectinghydrocarbon oil to conversion conditions of elevated temperature andsuperatmospheric pressure in a heating coil and communicating reactionchamber, separating the resulting vaporous and residual liquidconversion products, heating said residual liquid in a heating coil to atemperature sufliciently high toeffect its subsequent reduction to cokewithout allowing it suflicient time in the heating coil to permit anyexcessive formation and deposition of coke in this zone, introducing thehighly heated. residual liquid intoa coking chamber maintained atsubstantial superatmospheric pressure wherein it is reduced to coke,commingling the hot vaporous products from the coking chamber with saidvaporous conversion products, subjecting the commingled materials tocontinued conversion in a separate reaction chamber maintained atsubstantial superatmospheric pressure, separating the resulting vaporousand liquid conversion products, subjecting the latter to furthervaporization at substantially reduced pressure, returning the resultingresidual liquid to the heating coil of the coking system, subjecting thevaporous products of the process, including those evolved by saidfurther vaporization, to fractionation whereby their insufficientlyconverted components are condensed as reflux condensate, returning thereflux condensate to the ilrst mentioned heating coil for furtherconversion, subjecting fractionated vapors of the desired endboilingpoint to condensation and collecting and separating the resultingdistillate and gas.

Charging stock of any desired type may be employed and, depending uponits characteristics, may be supplied direct to the heating coil of thecracking system, to the heating coil of the coking system, to thefractionator or to the Vaporizing chamber following the last mentionedreaction chamber of the system.

The accompanying diagrammatic drawing i1- lustrates one form ofapparatus for carrying out the invention. Referring to the drawing,heating coil l is located Within a furnace 2 of any suitable form andthe oil supplied thereto for conversion, in the manner to be later morefully described, is subjected by means of heat suppliedfrom the furnacetothe desired conversion temperature, preferably at a substantialsuperatmospheric pressure; the heated products being discharged from theheating coil through line 3 and valve 4 into reaction chamber 5.

Reaction chamber 5 is also preferably maintained at a substantialsuperatmospheric pressure and, although not indicated in the drawing, ispreferably insulated to prevent the excessive loss of heat therefrom byradiation so that continued conversion of the heated products suppliedto this zone, and particularly their vaporous components, isaccomplished therein. In the particular case here illustrated, thestream of hot conversion products from heating coil I -is introducedinto the lower portion of chamber 5 wherein vaporous and liquidconversion products separate; the vaporous products passi-ng upwardthrough the chamber to be directed therefrom through line 6 and valve 'Ito reaction chamber 8, while the residual liquid conversion products arewithdrawn from the lower portion of chamber 5 through line 9 and valveI0 to pump II, byV

means of which they are supplied through line I2, valve I3 and line I4to heating coil I5. It will be understood, of course, that the inventionis not limited to the particular flow through the` reaction chamberillustrated inthe drawing. For example, the stream of hot conversionproducts from heating coil I may enter the upper portion of the reactionchamber, in which case both vaporous and liquid conversion products maypass Y downward through the chamber to be separately withdrawn from itslower portion, thus affording the liquid products a somewhat longercontinued conversion time in the reaction chamber. Other well knownalternative methods of ow through the reaction chamber may be employedwithin the scope of the present invention although, for

the sake of simplicity, they are not here illustrated. However, suchalternatives are not to be considered equivalent in all cases but may beselected to suit requirements. In any event, the vaporous and liquidproducts resulting from conversion in heating coil I and reactionchamber 5 are preferably separated at substantial superatmosphericpressure, the residual liquid prod-y I'I and valve I8, Without allowingthe oil suffi-l cient time in heating coil I5 to permit any excessiveformation and deposition of coke in this zone and in the linecommunicating with the coking chamber. Preferably, relatively high ratesof heating and relatively high velocities are employed in heating coilI5 to accomplish the desired results. However, this method of cokingheavy oils is not new, per se, with the present invention and need nottherefore be considered here in any great detail. v Y

Coking chamber I9 is also preferably operated at a substantialsuperatmospheric pressure which may be substantially the same, somewhathigher or somewhat lower than the pressure employed in reaction chamber'5. Although only one point offintroduction for-the materials to becoked into chamber I9 is illustrated in the drawing it will beunderstood that they may be supplied thereto at any desired point Aorplurality of points in this zone. Suicient time is afforded the highlycleaning of the chamber.

heated relatively heavy oils supplied to chamber I9 from heating coil I5to effect their reduction to substantially dry coke in this Zone, thecoke being allowed to accumulate within the chamber to be removedtherefrom in any well known manner, not illustrated, after the operationof the chamber is completed and preferably after it has been isolatedfrom the rest of the system. Chamber I9 is provided with a suitabledrain-line 20 controlled by valve 2I which may also serve, when desired,as a means of introducing steam, water or other suitable cooling mediuminto the chamber 'after its operation is completed and after it has beenisolated from the rest of the system in order to hasten cooling andfacilitate It is, of course, also within the scope of the presentinvention, although only one coking chamber is shown in the drawing, toemploy a plurality of such zones, one or more of which may be operatedwhile another or others are beingfcleaned and prepared for furtheroperation so that the duration of the operating cycle of the process isnot limited by the capacity of the coking zone.

In accordance with the provisions of the present invention hot vaporousproducts resulting from the coking operation in chamber Il are withdrawntherefrom through line 22 and valve 23 and arecommingled in line 6 withthe vaporous conversion products from reaction chamber 5, the commingledmaterials entering a separate reaction chamber 8, also preferablymaintained at a substantial superatmospheric pressure, wherein they aresubjected to continued conversion without additional heating. Chamber 8is also preferably insulated to minimize loss of heat by radiation,although this is not indicated in the drawing.

In the case here illustrated, the commingled vaporous products from thefirst reaction chamber and from the vcoking zone enter the upper portionof reaction chamber 8 and are subjected to predetermined continuedconversion time as they pass downward through this Zone, the resultingvaporous and liquid conversion products being withdrawn in commingledstate from the lower portion of chamber 8 through line 24 and suppliedthrough valve 25 to vaporzing chamber 26.y It is, however, within Ythescope of the present invention to employ any other desired flow throughchamber 8 which will afford the commingled vapors appreciable continuedconversion time in this zone and the vaporous and liquid conversionproducts may, when desired, be separately withdrawn from chamber 8,although such alternative means are not shown in the drawing.

Vaporizing chamber 26, in the case here illustrated, comprises the lowerportion of column 21, the upper portion of which comprises fractionator28, although separate structures may be employed, when desired, for thevaporzing and fractionating zones. Vaporizing chamber 26 is preferablymaintained at a substantially reduced pressure relative to that employedin reaction chamber 8 whereby further vaporization of the liquidconversion products supplied to this zone from chamber 8 isaccomplished. When vaporous and liquid conversion products are suppliedto chamber 26 it also serves as a zone of nal separation for thesematerials. The residual liquid conversion products remaining unvaporizedin chamber 26 are withdrawn therefrom through line 29 and valve 30 topump 3| by means of which they are fed through line 32 and may be ofhighly heated products from heating coil I or the residual liquidproducts from chamber 26 may, when desired, be separately supplied, allor in part, direct to coking chamber I8 at any desired point in thiszone by well known means not shown in the drawing or a regulated portionor all of this material may be withdrawn from the system, as one of thefinal products of the process,

, through line 55 and valve 65 to cooling and stor- 5 pending,

it is returned through line 40, valve 4I and linel 42 to heating coil I,for further conversion, in the manner already described.

Fractionated vapors of the desired end-boiling point are Withdrawn,together with uncondensable gas produced by the process, from the lowerportion of fractionator 28 through line 43 and valve 44 and aresubjected to condensation and cooling in condenser 45. The resultingdistillate and gas passes through line 45 and valve 41 to collection andseparation in receiver 48.

Uncondensable gas may be released from the receiver through line 49 andvalve 58. Distillate may be Withdrawn from receiver 48 through line 5|and valve 52 to cooling and storage or to any desired further treatment.When desired, a regulated portion of the distillate collected inreceiver 48 may be recirculated, by well known means, now shown in thedrawing, to the upper portion of fractionator 28 to serve as a refluxing:and cooling medium in this zone for assisting fractionation of thevapors and to maintain the desired vapor outlet temperature from thefractionator. f

As previously indicated, the present invention "permits the use of anydesired type of hydrocarbon oil charging stock ranging from crudepetroleum, topped or reduced crude and the like to heavy residual oils,including all of the various crude oil fractions such as straight-rungasoline, naphtha, kerosene or kerosene distillate, gas oil, fuel oiland the like or mixtures of Such materials as Well asvarious crackedproducts such as pressure distillate, pressure distillate bottoms,reflux condensates and cracked residual oils. The charging stock issupplied, in the case here illustrated,

through line 53 "and valve 54 to pump 55 by means of which it is fedthrough line 56 and may be supplied, all or in part, through line 51 andvalve 58 into fractionator 28 or through line IEl, line 58 and valve 88into vaporizing chamber 26 or through line 6I, valve 62 and line I4 toheating coil I5 or from line 6I through line 63, valve 64 and line 42 toheating coil I, the method of supplying the charging stock to the systemdeprimarily, upon its characteristics.

Preferably., only charging stock of relatively highboilingcharacteristics is supplied Adirect to heating coil I5 and only chargingstock of relatively low-boiling characteristics is supplied direct toheating coil I. Charging Stock of any desired characteristics maybesupplied to the fractionator so long as it contains no appreciablequantity of high-boiling components of a high cokeforming natureunsuitable for conversion in heating coil I and no appreciable quantityof lowboiling fractions within the range of the desired nal motor fuelproduct of the process but of unsatisfactory quality, particularly withrespect to antiknock value, the latter qualication also applying to anycharging stock supplied to vaporizing chamber 26, although this is theonly limitation with respect to the type of charging stock which may beSupplied to this zone.

The preferred range of operating conditions which may be employed in thepractice of the present invention in an apparatus of the generalcharacter illustrated and above described may be approximately asfollows: The heating coil 'of the cracking system may employ an outletconversion temperature ranging, for example, from 850 to 1050 F.,preferably with a substantial superatmospheric pressure at this point inthe system of from 100 to 500 pounds, or more, per square inch. Anydesired pressure within substantiallyl the same range but no greaterthan that employed at the outlet from the heating coil may be utilizedin the rst reaction chamber and may be substantially equalized orsomewhat reduced in the second reaction chamber. The heating coil of thecoking system may employ an outlet conversion temperature ranging, forexample, from 900 to 1050o F., preferably with a superatmosphericpressure of from 100 to 500 pounds, or thereabouts, per square inchwhich pressure may be substantially equalized or somewhat reduced in thesucceeding coking chamber. The vaporizing chamber is preferably operatedat a substantially reduced pressure relative to that employed inthe lastreaction chamber, ranging, for eX ample, from 100 pounds, orthereabouts, per square inch down to substantially atmospheric pressure.The fractionating, condensing and collecting portions of the system mayemploy pressures substantially the same or somewhat lower than thatutilized in the vaporizing chamber.

The following is a specic example of one of the many possible operationsof the process of the p-resent invention as it may be accomplished in anapparatus ofthe character illustrated and above described, utilizing ascharging stock a Mid-Continent topped crude of about 30 A. P. I.gravity, which is supplied to thevaporizing chamber: Reflux condensatefrom the fractionator of the cracking system, including the componentsof the charging stock vaporized in thevaporizing chamber andsubsequently condensed in the fractionator, as. well as the intermediateconversion products of the process which are condensed in thefractionator as reflux condensate, is subjected in the heating coil ofthe cracking system to an outlet conversion temperature of approximately950 F. at a. superatmospheric pressure of about 350 pounds per squareinch. This pressure is substantially equalized in the succeeding.

reaction chamber. Theresidual liquid conversion products from the firstreaction chamber are quickly heated 'in a'separate heating coil,together with residual liquid from the vaporizing chamber (the latterincluding 'some highboiling components of the charging. stock remainingunvaporized in this zone) to ,an outlet temperature of approximately1000o F. at a superatmospheric pressure of about 250 pounds per squareinch. Substantially the same pressure is maintained in the cokingchamber and in the second reaction chamber, to which vaporous productsfrom the coking chamber and from the first mentioned reaction chamberare supplied for further conversion. The vaporizing chamber is operatedat a superatmospheric pressure of approximately 30 pounds per squareinch. This pressure is substantially equalized in the succeedingfractionating, condensing and collecting portions of the system. Thisoperation may produce, per barrel of charging stock, approximately 68per cent of motor fuel having an antiknock value equivalent to an octanenumber of approximately 70 by the motor method and approximately 75pounds of low volatile coke of substantially uniform quality, theremainder being chargeable, principally, to uncondensable gas and loss.

I claim as my invention:

1. In a process for the conversion of hydrocarbon oil wherein the oil issubjected to cracking conditions of elevated temperature andsuperatmospheric pressure, the resulting vaporous and liquid conversionproducts separated and the latter subsequently subjected to coking at aternperature of from 900 to 1050 F. and under substantialsuperatrnospheric pressure of from 100 to 500 pounds per square inch,the improvement which comprises commingling the vaporous products fromthe coking operation with the vaporous products previously separatedfrom the liquid conversion products subjected to said coking andsubjecting the commingled vapors, yin a zone maintained at conversiontemperature, to continued cracking at substantial superatmosphericpressure for a predetermined time without additional heating.

2. In a process for the conversion of hydrocarbon oil wherein the oil issubjected to cracking conditions of elevated temperature andsuperatmospheric pressure, the resulting vaporous and liquid conversionproducts separated, the latter subjected to additional heating andcoking at a temperature of from 900 to 1050 F. and under substantialsuperatmospheric pressure of from 100 to 500 pounds per square inch, theimprovement which comprises commingling the vaporous products from thecoking operation with the vaporous products previously separated fromthe liquid conversion products subjected to said coking and subjectingthe commingled vapors, in a zone maintained at conversion temperature,to continued cracking at substantial superatmospheric pressure for apredetermined time without additional heating.

3. In a process for the conversion of hydrocarbon oils wherein an oil issubjected to cracking conditions of elevated temperature andsuperatmospheric pressure, the resulting vaporous and liquid conversionproducts separated and the latter subsequently subjected to coking athigh temperature of from 900 to 1050 F. and substantial superatmosphericpressure of from 100 to 500 pounds per square inch, the improvementwhich comprises comrningling the vaporous products from the cokingoperation with the vaporous products previously separated from theliquid conversion products subjected to said coking, subjecting thecommingled vapors, in a zone maintained at conversion temperature, tocontinued cracking at substantial superatmosphcric pressure, whereinvaporous and liquid conver-` sion products separate and wherein thevapors are subjected to continued conversion time, thev improvementwhich -v comprises withdrawing residual liquid conversion products fromthe reaction chamber, heating the same in a separate heating coil to atemperature suiliciently high to effect their subsequent reduction tocoke Without allowing them suicient time in the heating coil to permitthe excessive formation and deposition of coke in this zone, introducingthe highly heated residual liquid into a coking chamber, maintainingsaid separate'coil and coking chamber under substantial superatmosphericpressure of from 100 to 500 pounds per square'l inch, reducing theheated residual products to coke in the coking chamber, withdrawing hotvaporous products from the cokingchamber, cominingling the same with thevaporous conversion products from the reaction chamber and subjectingthe commingled vapors to continued cracking at substantialsuperatmospheric pressure in a separate unheated reaction chambermaintained at conversion temperature by the heat of the vaporousproducts, separating the resulting vaporous and liquid conversionproducts, sub-" jecting the vapors'to fractionation, whereby theirinsuiciently converted components are condensed as reiiux condensate,returning the reiiux condensate to the first mentioned heating coil forfurther conversion, subjecting fractionated vapors of the desiredend-boiling point to condensation and collecting the resultingdistillate.

5.V In a process for the conversion of hydrocarbon oils wherein an oilis subjected to cracking conditions of elevated temperature andsuperatmospheric pressure in a heating coil, the heated productsintroduced into an' enlarged reaction chamber, also maintained at'superatmospherlc pressure, wherein vaporous and liquid conversionproducts separate and the vapors are sub-` jected to continuedconversion time, the improvement which comprises withdrawing residualliquid conversion products from the reaction chamber, heating the samein a separate heating coil' to a temperature suiiiciently high to eiecttheir subsequent reduction to coke without allowing them suflicient timein the heating coil to permit the excessive formation and deposition ofcoke in this zone, introducing the highly heated residual liquid in'tolla coking? chamber, maintaining said separate coil and coking chamberundersubstantial superatmospheric pressure of from 100 to 500 pounds persquare inch, reducing the heated residual products to coke in the cokingchamber, withdrawing hot vaporous products from the coking chamber,commingling the same with the vaporous conversion products from thereaction chamber and subjecting the commingled vapors to continuedcracking at substantial superatmospheric pressure in a separate unheatedreaction chamber -maintained at conversion temperature by the heat ofthe vaporous products, separating the resulting vaporous and liquidconversion products, subjecting the latter to further vaporization atsubstantially reduced pressure, subjecting the vaporous conversionproducts, including 5 wherein residual liquid resulting from saidfurther vaporization of the liquid conversion products from the lastmentioned reaction chamber are returned to the heating coil of thecoking system.

8. A process of the character defined in claim 5 wherein hydrocarbon oilcharging stock for the process is supplied to the iirst mentionedheating coil.

9. A process of the character defined in claim 5 wherein hydrocarbon oilcharging stock for the process, comprising an oil of relativelyhighboiling characteristics, is supplied to the heating coil of thecoking system.

10. A process of the character dened in claim 5 wherein hydrocarbon oilcharging stock for the process is supplied to the vaporizing chamber.

1l. A process of the character defined in claim 5 wherein hydrocarbonoil charging stock for the process is supplied to the fractionatingzone.

12. A conversion process which comprises subjecting hydrocarbon oil tocracking conditions of temperature and pressure in a cracking zone,separately removing vapors and unvaporized oil from said Zone, heatingand coking the unvap-orized oil at temperatures of from 900 to 1050 F.and under pressures of from to 500 pounds per square inch, combiningvapors evolved by such heating and coking of the unvaporized oil withvapors removed from the cracking zone, subjecting the commingledvapors., in a Zone maintained at conversion temperature to continuedcracking under superatmospheric pressure by the heat contained in thevapors and without additional heating thereof, and fractionating andcondensing the vaporous products of said continued conversion.

13. A conversion process which comprises subjecting hydrocarbon oil tocracking conditions of temperature and pressure in a cracking zone,separately removing vapors and unvaporized oil from said zone, passingthe unvaporized oil through a heating coil and heating the same thereinto a temperature of from 900 to l050 F., discharging the thus heated oilinto a coking zone and distilling the same to coke therein, maintainingsaid coil and coking zone under pressure of from 100 to 500 pounds persquare inch, combining the vapors evolved in the coking Zone with thoseremoved from the cracking zone, subjecting the commingled vapors, in azone maintained at conversion temperature to continued cracking undersuperatmospheric pressure by the heat contained in the vapors andwithout additional heating thereof, and fractionating and condensing thevaporous products of said continued conversion.

14. A process for cracking hydrocarbon oil which comprises passing theoil through a heating zone and heating the same therein sufciently tovaporize a substantial portion thereof, introducing the heated oil intoan enlarged separating zone and therein separating the same into vaporsand liquid, removing the liquid from the separating zone and crackingthe same at a temperature of from 900 to 1050 F. under a pressure offrom 100 to 500 pounds per square inch, introducing resultant crackedvapors and the rst-named vapors to an unheated reaction zone maintainedat cracking temperature by the heat of the vapors, subjecting thecommingled vapors to cracking under superatmospheric pressure in thereaction zone by the heat contained in the vapors and without additionalheating thereof, and then removing the vapors from the reaction zone andsubjecting the same to fractionation and condensation.

KENNETH SWARTWOOD.

